[AQ]

Istanbul was one of my favourite destinations when I was working. It is quite a safe city and very cosmopolitan. Although, as with all cities, at night there are some places it is better not to go to. Your hotel will advise. It is also very big but if you are staying in the centre the buses and trams are good and the taxies are not expensive.

It has some of the best fish restaurants in Europe.

I assume you have been told about the £10 "visa" you have to buy on entry before passport control. There can be very long queues at passport control on leaving.

Check the weather forecast as it can be very cold and snowy at this time of year.

Finally to answer you questions I would not take the flash gun and if you only take one lens the 28-200 will give you more options.